In conventional wireless cellular networks, the initial rollout typically involves installation of macro stations to provide wireless cellular coverage for mobile units. A macro base station comprises multiple transceiver units, outputs relatively high power (i.e. 10 watts or more) to its antenna(s) and is communicatively coupled to a telephone network via a backhaul connection. The backhaul connection includes a T1 connection (in the United States) or an E1 connection (in Europe) to a base station controller which is, in turn, connected to the telephone network. Because macro base stations output high power, they can provide large areas of coverage.
The capacity of a macro base station can be expanded to a limited degree by the addition of transceivers and antennas to the macro base station. Additional macro base stations can also be added to the cellular network. However, these measures have limitations due to interference among macro base stations due to their large coverage areas and high output power.
A solution to this capacity problem has been to add micro or pico base stations to the cellular network. Similarly to a macro base station, a micro base station comprises multiple transceiver units and is communicatively coupled to a telephone network via a backhaul connection. However, compared to the output power of a macro base station, a micro base station outputs relatively low power (i.e. 1-2 watts) to its antenna(s). A pico base station is also communicatively coupled to a telephone network via a backhaul connection, but comprises only a single transceiver unit and typically uses an Internet protocol (IP) backhaul connection in which voice signals are converted to IP packets. A pico base station outputs relatively low power (i.e. less than one watt) to its antenna. Pico base stations can be located indoors, such as in offices, shopping centers, convention centers, and airports.
A drawback to this approach for adding capacity to the network is that the micro or pico base stations are located at sites where the additional capacity is needed and therefore require additional infrastructure for each site. Furthermore, they are not easily accessible for maintenance or upgrades. Also, because an additional backhaul link is required for each micro or pico base station, the backhaul links tend to increase installation and maintenance expense.